Rail Vehicle Structural Link Energy Absorption
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Solution Overview
Problem
Existing structural links for rail vehicle assemblies face challenges in maintaining effective energy absorption and alignment during collisions, particularly when the coupling rod is angled relative to the reference axis, due to the protrusion of the bushing outside the energy-absorption unit, which can hinder piston head motion.
Innovation Solution
The structural link incorporates a piston rod with an outer cylindrical sliding surface and an annular guide fixed to the energy absorption unit, allowing the piston head to maintain alignment and effect radial expansion of the deformable cylinder without requiring the cylinder to exceed the piston head's stroke length, with a press-fitted connection and axial preload ensuring proper operation within defined collision and service limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the bushing protrudes outside the widened portion of the energy-absorption unit to accommodate the coupling rod articulation, then the coupling rod can articulate freely, but the bushing may hinder the stroke motion of the piston head into the permanently deformable cylinder when the coupling rod is at an angle during collision
Solution Approach 1:
The guide is repositioned from protruding outside the energy-absorption unit to being contained within the permanently deformable cylinder. This spatial reconfiguration allows the coupling rod to articulate freely at the bushing while the guide remains inside the cylinder to guide the piston head's linear stroke motion without interference
Solution Approach 2:
The guide is separated into a distinct component that can be independently positioned within the permanently deformable cylinder, rather than being integrated into the bushing structure. This segmentation allows the guide to fulfill its alignment function for the piston head while the bushing independently accommodates the coupling rod articulation
2Device complexity
If the permanently deformable cylinder is made longer than the piston head stroke to accommodate the guide in the end position, then the guide can be accommodated, but the overall length of the energy absorption unit increases
Solution Approach 1:
The guide is nested within the permanently deformable cylinder, with the guide's outer surface fitting inside the cylinder's inner surface. This nesting arrangement allows the guide to be contained within the cylinder's length, eliminating the need for the cylinder to extend beyond the piston head's stroke distance
3Quantity of substance
If the bushing is positioned very close to the widened portion of the energy-absorption unit in the service position, then the structure is compact, but this arrangement may hinder the stroke motion of the piston head when the coupling rod is at an angle during collision
Solution Approach 1:
The guide function is extracted from the bushing structure and implemented as a separate guide component within the permanently deformable cylinder. This extraction allows the bushing to be positioned compactly near the widened portion for coupling rod articulation while the guide ensures reliable piston head stroke motion during collision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design ensures reliable energy absorption and alignment during collisions while preventing deformation or play, even under standard proof and fatigue loads, by allowing the piston head to move radially within the deformable cylinder and maintaining structural integrity through predetermined thresholds and preloads.
Implementation Method 1
the piston head is such as to effect a radial expansion of the permanently deformable cylinder while moving parallel to the reference axis within the permanently deformable cylinder
Implementation Method 2
the annular guide is fixed relative to the widened portion of the energy absorption unit and has an inner diameter such as to be in sliding contact with the outer cylindrical sliding surface of the piston rod
Implementation Method 3
The annular guide in the service position is press-fitted onto a cylindrical seat of the piston rod
Data Source
Figure 1~2
Figure 3~4
Figure 5~8
AI summary
A permanent structural link (18) for permanently linking a first subassembly of a rail vehicle assembly with a second subassembly of the rail vehicle assembly, comprises: an energy absorption unit (20) comprising a permanently deformable cylinder (28), which defines a reference axis (100) and a widened portion (30), which has an inner cross-sectional area greater than the permanently deformable cylinder (28), a piston (24) comprising an end portion (44) provided with a non-deformable piston head (52), wherein the piston head (52) in a service position is received in the widened portion (30) of the energy absorption unit (20), wherein the piston head (52) is such as to effect a radial expansion of the permanently deformable cylinder (28) while moving within the permanently deformable cylinder (28) in a stroke direction (200) parallel to the reference axis (100), and an annular guide (58) for guiding a relative translation motion between the piston (24) and the permanently deformable cylinder (28) in the stroke direction (200). The piston (24) comprises a piston rod (42) protruding from the end portion (44) in a direction parallel to the reference axis (100) and opposed to the stroke direction (200). The piston rod (42) is provided with an outer cylindrical sliding surface (74), and the annular guide (58) is fixed relative to the widened portion (30) of the energy absorption unit (20) and has an inner diameter such as to be in sliding contact with the outer cylindrical sliding surface (74) of the piston rod (42).